Acetochlor as a soil pollutant

Abstract

Acetochlor is a widely used herbicide all over the world. Similarly to other organic pollutants, the environmental fate of the acetochlor is strongly related to its adsorption properties. Static adsorption equilibrium measurements were carried out at 25 degrees C on different types of Hungarian soils characterized by varying amounts of organic matter and pH values. Isotherms obtained under different conditions, as well as on various soils, exhibit a similar shape, thus indicating a two-step adsorption process. The plots cannot be interpreted according to the classes of isotherms suggested by Giles. The adsorption coefficients (K) were estimated from the initial slope of the curves. These values were determined not only by the type of the soil, but also by the composition of the aqueous media. The organic matter adsorption coefficients (Kom) were also calculated and they were approximately identical for soils of high organic matter. Due to the low value of the adsorption coefficients, the acetochlor is a rather mobile pollutant of the soil posing a potential danger to the aquatic environment. For soils with high organic content, the Kom values are similar to each other and, due to the significant coverage of the inorganic surfaces, the adsorption is controlled by the solute-organic substance interactions. The adsorption of weakly polar compounds, however, is remarkable even on those soils where the organic content is low. In this case, the binding is governed by the solute-inorganic surface interactions. This conclusion is nicely proved by the adsorption of the acetochlor on quartz. According to our hypothesis, the second part of the adsorption step is controlled by the solute-adsorbed solute interactions. The role of the organic matter in this region of the isotherm is probably negligible. As the organic matter content of the soils plays an important role in the acetochlor adsorption, humic substances must have a strong influence upon the transport of this compound. Experiments to obtain adsorption isotherms of further pesticides and the development of a quantitative model are in progress.

Effect of soil and sediment composition on acetochlor sorption and desorption

“…Although acetochlor is one of the most frequently used herbicides in Slovakia, there is no data referring to its sorption behavior in natural solids. Even throughout the world, only a little data is available for acetochlor sorption (Kholodov et al 2005;Lengyel and Földényi 2003;Liu et al 2000;Wang et al 1999;Zheng and Ye 2002) and very little for its desorption (Taylor et al 2004). Previous studies based on soil column and sorption experiments have shown that acetochlor presents a risk of groundwater contamination (Balinova 1997;Zheng and Ye 2002), consistent with its frequent presence observed in groundwater (Barbash et al 2001;Kolpin et al 1996Kolpin et al , 1998.…”

Degradation of acetochlor by a bacterial consortium of Rhodococcus sp.T3-1, Delftia sp.T3-6 and Sphingobium sp.MEA3-1

“…In the river water, acetochlor was difficult to hydrolysis and the half‐life is more than 1386 days (Zheng and Ye ). Due to its low adsorptive potential in soils, heavily applied acetochlor was rather mobile, posing a potential risk to the aquatic (Lengyel and Földényi ). Studies have proved the presence of acetochlor in groundwater as well as in surface water (Kolpin et al .…”

Effects of exposure to acetochlor on the expression of thyroid hormone related genes in larval and adult rare minnow (Gobiocypris rarus)

“…Acetochlor (2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide) is a common herbicide all over the world (Lengyel and Foldenyi, 2003), which has been widely used in China (Ye, 2003). Previous studies have demonstrated the presence of acetochlor in surface water (Hladik et al, 2008), soil (Chao et al, 2007), and sediment (Xue et al, 2005).…”